1. Field of the Invention
This invention relates to a rear suspension of an automobile and, more particularly, to a rear suspension comprising a suspension arm connected pivotably to a car body by two supports spaced from each other longitudinally of the car body and supporting pivotably an axle carrier by two supports spaced from both said supports laterally of the car body.
2. Description of the Prior Art
A suspension has been proposed which comprises a suspension arm having a generally L-shape as viewed in plan, pivotably connected to a car body through bushings disposed in inward front and rear supports and supporting pivotably an axle carrier at outward front and rear supports (Japanese published examined Patent application-2nd Publication (Tokkyo Koo) No. 38762/79). According to the suspension, respective support points are located to meet such requirements that a straight line interconnecting the rear support point at the car body side and the rear support point at the axle carrier side is orthogonal to a center line of a grounding face of a wheel and a straight line interconnecting the front and rear support points at the car body side makes a predetermined cross angle with respect to a center line of the car body.
With the suspension noted above, arm portions of the suspension arm extending laterally and longitudinally are formed to be rigid. Thus, when a wheel supported by the suspension arm is forced laterally or longitudinally, the degree of displacement of the wheel is affected in either case by the hardness of bushings disposed in the front and rear supports of the suspension arm at the car body side. Therefore, proper lateral rigidity is difficult to ensure while maintaining proper longitudinal compliance. As a result, it is not easy to ensure the strength of the suspension and car body member on one hand while improving riding comfort and controllability on the other hand.
Next, with said suspension, the straight line interconnecting the front and rear support points of the suspension arm at the car body side, i.e., a swing axis of the suspension arm is not parallel to the axes of the bushings disposed in the respective supports, but intersects the same at a certain angle. Accordingly, when the suspension arm is swung, a pinching force acts on each of the bushings to cause degradations of durability and vertical rigidity of the bushing.
According to an independent rear suspension disclosed in the Utility Model Public Disclosure (KOKAI) No. 192805/82, one of the bifurcated arm portions provided on a trailing arm is formed so as to be undeformable or rigid vertically and deformable laterally. Thus, while the controllability may be improved, the same problems as the suspension noted above are encountered in such points that the lateral and longitudinal displacements of the wheel are affected by the hardness of bushings disposed respectively in the bifurcated arm portions and the hardness of a bushing disposed in the car body side of a rod which is connected at one end thereof to the trailing arm and at the other end to the car body for restricting a lateral motion of the trailing arm.
According to a rear suspension disclosed in the Patent Public Disclosure (KOKAI) No. 53215/84, an arm portion disposed longitudinally is formed so as to be deformable vertically and undeformable laterally. Then, it is difficult to ensure the proper lateral rigidity and the vertical rigidity may be degraded.